• 대한치과보철학회:학술대회논문집
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• 1996.11a
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• pp.106-107
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• 1996

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.38-48
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• 2011

Purpose: Dentists suffer back, neck and shoulder pain during their careers due to bad operating posture. If dentists have a good operating posture ergonomically, there would be less pain and discomfort in the shoulder and back. Therefore, dentists should learn the Home position which enables dentists to approach a stable posture ergonomically. This study was to compare tooth preparation in the Home position and the Random position, and evaluate the clinical efficacy of the Home position. Materials and methods: Tooth preparation for fixed partial denture was performed on the maxillary left 2nd premolar and maxillary left 2nd molar at the two different operating positions were compared. The amount of occlusal reduction, marginal width, subgingival margin depth, and convergence angle were measured. A T-test was performed separately to compare the results of the Random position and the Home position. Results: 1. The amounts of average thickness of occlusal reduction on fossa were deficient to the ordered ones in the Random position and the Home position (P > .05). 2. The average subgingival margin depth of prepared margin on maxillary left 2nd premolar, maxillary left 2nd molar were excessive in the Random position than in the Home position. On the maxillary left 2nd premolar, there was no statistical difference in the Random position and the Home position except Distal midline, DL line angle, Lingual midline, ML line angle (P< .05). On the maxillary left 2nd molar, there was no statistical difference in the Random position and the Home position (P < .05). 3. Average convergence angle in the Random position and the Home position were excessive compared to the ordered angle. There was no statistical difference in the Random position and the Home position (P > .05). 4. Analysis of pearson correlation : In the Random position, the amounts of average thickness of occlusal reduction, the average subgingival margin depth of prepared margin, convergence angle were significantly associated with each other (P < .05). But in the Home position, they were not significantly associated with each other (P < .05). 5. The time needed for preparation in the Home position was faster or equal than that of the Random position as time went on. Conclusion: In conclusion, there were no significant differences between Home position and Random position in measures of occlusal reduction, marginal width, marginal depth, convergence angle. However, preparation time and incidence of damaging adjacent teeth were less in Home position than in Random position. Therefore, if trained properly, Home position which is more ergonomically stable can be adopted for clinical use.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.728-734
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• 2001

The purpose of this study was to investigate the effects of Er:YAG laser on cutting of efficacy of enamel and dentin in primary and permanent teeth. We used the enamel and dentin specimens of human teeth which contain the physiologic saline and maintain the pulpal pressure in dentinal tubules. Each specimen was exposed to Er:YAG laser with non-contact mode under different treatment condition of irradiation energy, pulse repetition rate. We investigated the cutting efficacy of Er:YAG laser by Scanning Intensity Microscopy, and obtained following results. 1. Cutting volume of enamel and dentin in primary and permanent teeth were increased by increasing the irradiation energy, pulse repetition rate. 2. Cutting volume of primary teeth was larger than that of permanent teeth. 3. Cutting volume of dentin was larger than that of enamel in primary and permanent teeth. From these results, Er:YAG laser would be more effective in cutting dentin than enamel, and in cutting primary teeth than permanent teeth for clinical application.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.1
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• pp.64-75
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• 2019

The purpose of this study was to obtain instructions for size selection of prefabricated crown and tooth reduction by 3-dimensional analysis of the size and shape of the maxillary primary central and lateral incisors and prefabricated crowns (celluloid strip, resin veneered stainless steel, and zirconia crowns). The maxillary primary central and lateral incisors of 300 Korean children was scanned with three types of prefabricated crown to create standard three-dimensional tooth models and prefabricated crowns. The shapes of the prefabricated crowns and natural teeth were compared according to four parameters (mesio-distal width, height, labio-palatal width, and labial surface curvature coefficient) and calculated the amount of tooth reduction required for each prefabricated crown. The size 2 resin veneered stainless steel crown, size 1 zirconia crown, and size 2 celluloid strip crown were most similar in shape to the primary central incisor. The size 3 rein veneered stainless steel crown, size 2 zirconia crown, and size 3 celluloid strip crown were most similar to the primary lateral incisor. The amount of tooth reduction was similar in both maxillary primary central and lateral incisors. The incisal reduction was greatest for the zirconia crown. At the proximal surface, the zirconia and celluloid strip crowns required a similar amount of tooth reduction, but more than the resin veneered stainless steel crown. The labial surface reduction was greatest for the zirconia crown. The degree of lingual surface reduction was not significant among the three prefabricated crowns. Among the assessment parameters, mesio-distal crown width was the most important for choosing a prefabricated crown closest to the actual size of the natural crown.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.2
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• pp.191-200
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• 2012

The patients' demand for treatment of unesthetic anterior teeth is steadily growing. Accordingly, several treatment options such as porcelain laminate veneers(PLV) have been proposed to restore the esthetic appearance of the dentition. Porcelain laminate veneers are considered minimally invasive, but they also require removal of sound enamel. One critical step in the porcelain laminate veneer technique is the achievement of sufficient ceramic thickness, and several different strategies for tooth preparation can be found in the literature. This clinical report describes a step-by-step protocols for preparation of these restorations used with the silicone index from diagnostic wax-up and the acrylic resin mock-up. Conservative use of porcelain laminate veneers provided satisfactory esthetic outcomes and preserved sound tooth structure.

• Restorative Dentistry and Endodontics
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• v.34 no.3
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• pp.232-239
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• 2009

The aim of this study was to compare the effects of anti curvature filing with stainless steel k-file versus nickel-titanium ProFile in the shaping of mesial root canals of extracted mandibular molars. A total of 60 canals from 30 mesial roots of mandibular molar teeth were randomly assigned to three groups with n=20 each. They were prepared with different instruments and methods: The first group with stainless steel k-file and circumferential filing. the second with precurved stainless steel k-file and anticurvature filing and the third with ProFile C06 taper) and anticurvature filing. Using a micro-computed tomography system (skyscan-1076, SKYSCAN, Antwerpen, Belgium), pre-and post-operative specimens were scanned. Subsequently, canal images were superimposed and changes in root dentin thickness were measured at distal side (danger zone) of the canal. The data was analyzed using a one-way ANOVA and the comparison of means was conducted using a post hoc multiple comparison Tukey test. There were significant differences in the change of root dentin thickness at the $7.5{\sim}8.5\;mm$ level between group 1 and 2, $3.5{\sim}6mm$ level between group 1 and 3 and $3.5{\sim}6mm$ level between group 2 and 3(n=20, P<0.05).

• Journal of Oral Medicine and Pain
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• v.30 no.3
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• pp.375-381
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• 2005

Er:YAG laser has been considered a promising alternative to dental drill and many researches indicate that adjustment to variable parameters, including water flow rate, pulse energy and pulse repetition rate, can be made to improve ablation ability and efficiency of the laser. Of these parameters, addition of water spray during irradiation has been thought to ablate dental hard tissue more rapidly and safely. The purpose of this study was to investigate tooth ablation amount by Er:YAG laser irradiation as related to varied water flow rates added and, ultimately to find the most effective water flow rate for ablation. In addition, the temperature change of pulp chamber during irradiation was also monitored on the irradiated and opposite pulpal walls, respectively. An Er:YAG laser with contact mode was employed. Extracted human molars were split into two pieces for ablation experiment. Pulse energies of 200 and 300 mJ with a pulse repetition rate of 20 Hz and 5 water flow rates (1.6, 3.0, 5.0, 7.0, and 10.0 ml/min) were applied. Each irradiation was performed for 3 seconds. According to these parameters, experimental groups were divided into 10 subgroups which consisted of 5 specimens. For temperature experiment, another 5 tooth-specimens were prepared in the manner that pulp chamber was open through access cavity preparation and two temperature-measuring probes were placed respectively on the irradiated and the opposite walls of pulp chamber. From the experiment on ablation amount related to different water flow rates, it was shown that the least water flow rate of 1.6 ml/min ablated more than any other water flow rates (p<0.000). When the irradiation for 3 seconds, combined with the pulse repetition time of 20Hz and the water flow rate of 1.6 ml/min was done to tooth specimen, the temperature rise was not noticeable both on the irradiated and the opposite pulpal walls (less than 3$^{\circ}C$) and there was no significant difference in temperature rise between the two pulse energies, 200 and 300 mJ. From the results of this study, it is suggested that tooth ablation with Er:YAG laser can be done effectively and safely at a energy between 200 and 300 mJ/pulse and a pulse repetition rate of 20 Hz when the lasing is conjugated with the water flow rate of 1.6ml/min.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.2
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• pp.152-160
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• 2011

Purpose: The aim of this study was to evaluate the volumetric change of teeth after preparation for various designs and margin locations through Micro CT analysis (Skyscan 1076: SKYSCAN, Konitch, Belgium). Materials and methods: The 36 artificial teeth were used to determine reduction volume of upper central incisor. According to the restorative design these 36 teeth were divided into 4 groups and according to the marginal location each group was divided into 3 subgroups. The volume of unprepared teeth was obtained by using Micro CT and the volume of prepared teeth was obtained in the same method. The CT scanned images before and after preparation were superimposed. Results: The volume difference was significantly increased as follows: traditional laminate veneer < full laminate veneer < all ceramic crown < metal ceramic crown. One-way ANOVA and Tukey multiple comparison analyses were used to analyze the data in this study. In each group the volume difference was significantly increased as follows: 1 mm above CEJ < CEJ < 1 mm below CEJ (P<.05). The % volume difference of all ceramic crown and metal ceramic crown was 31 - 48% and that of laminate veneer was 14 - 30%. The volume difference of the traditional laminate veneer was 1/3 of that of metal ceramic crown. The full laminate (1 mm below CEJ) and all ceramic crown (1 mm above CEJ) showed a similar volume difference. Metal ceramic crown showed 13.7% more volume difference than all ceramic crown. Conclusion: There exists the difference in volumetric change according to designs of restoration and margin locations of preparation.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.05a
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• pp.289-292
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• 2018

데이터베이스는 대용량의 데이터를 효율적으로 관리할 수 있는 장점을 가지고 있기 때문에 다양한 분야에서 사용되고 있다. 관련 범죄 발생 시 PC, 스마트폰 등 다지털 기기의 정보를 수집, 복구, 분석해 활용하는 '디지털포렌식'을 이용하여 수사가 진행된다. 이 때 삭제된 데이터의 복구가 중요하며 관련 연구가 많이 진행되고 있지만 삭제 방법보다 복구 방안에 초점을 두고 진행하는 경우가 많다. 따라서 본 논문에서는 실제 수사에서 데이터 복구 실패한 사례를 통해 기존 연구된 삭제된 레코드 복구 기법 방식을 실험한다.

• 대한치과보철학회:학술대회논문집
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• 1999.11a
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• pp.64-64
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• 1999